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A Microfluidic Approach for the Study of Ice and Clathrate Hydrate Crystallization
Published on: August 18, 2022
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A continuum of amorphous ices between low-density and high-density amorphous ice
Ali Eltareb1,2, Gustavo E Lopez3,4, Nicolas Giovambattista5,6,7
1Department of Physics, Brooklyn College of the City University of New York, Brooklyn, NY, 11210, USA. ali.eltareb@brooklyn.cuny.edu.
Communications Chemistry
|February 20, 2024
Summary
Computer simulations reveal a continuum of amorphous ices, including intermediate amorphous ices (IA), generated by isobaric cooling. The IA produced at 125 MPa closely resembles medium-density amorphous ice (MDA), suggesting MDA is not unique.
Area of Science:
- Physical Chemistry
- Materials Science
- Computational Physics
Background:
- Amorphous ices are typically classified as low-density (LDA) or high-density (HDA) forms.
- Recent experiments produced medium-density amorphous ice (MDA) via ball-milling, complicating the understanding of water's phase diagram.
- The existence and formation pathways of various amorphous ice densities require further investigation.
Purpose of the Study:
- To investigate the formation of amorphous ices under different pressure conditions using computer simulations.
- To explore the density range and structural properties of amorphous ices produced by isobaric cooling and compression/decompression.
- To understand the relationship between LDA, HDA, MDA, and newly identified intermediate amorphous ices (IA) within the potential energy landscape.
Main Methods:
- Performed extensive computer simulations of water under isobaric cooling and isothermal compression/decompression.
- Analyzed the densities and structural characteristics of the generated amorphous ice phases.
- Utilized the potential energy landscape (PEL) formalism to interpret the nature and stability of different amorphous ice forms.
Main Results:
- Isobaric cooling can produce a continuous range of amorphous ices (IA) with densities between LDA and HDA, depending on applied pressure.
- The intermediate amorphous ice (IA) generated at approximately 125 MPa exhibits density and structural similarity to experimentally produced MDA.
- LDA and HDA occupy distinct regions in the PEL, while IA forms in the intermediate region separating them.
Conclusions:
- The discovery of a continuum of amorphous ices challenges the discrete LDA/HDA classification.
- Medium-density amorphous ice (MDA) is likely not a unique phase but rather representative of intermediate amorphous ices (IA) formed under specific conditions.
- The potential energy landscape provides a framework for understanding the formation and relationships between different amorphous ice densities.
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